I haven't tried that many, but here are my opinions in those that I have tried. 1) Ralph Lauren Polo --- collars don't stay in shape after repeated washings, plus I don't fancy the polo player very much. The fabric also gets washed too easily. 2) Loro Piana --- I really like the cut and fabric, but plastic buttons... The one-piece collar is great for polo and sport shirts for me. Looks brand new even after repeated laundering. 3) Hermes --- light fabric, chest pocket (with 'H' embroidered), slightly longer than the Loro Piana polo. I like the pearl buttons but I don't like the flimsy collar. The fabric also creases easily. 4) Cucinelli --- leather zipper, slim, textured fabric. Really like it, though I'd still prefer buttons to zipper. What are your favourites?